PubMed HealthSearch

PubMed · 10320942

Cell migration as a five-step cycle.

Abstract

The migration of cells over substrata is a fundamental and critical function that requires the co-ordination of several cellular processes which operate in a cycle. At the level of the light microscope, the cycle can be divided into five steps: (1) extension of the leading edge; (2) adhesion to matrix contacts; (3) contraction of the cytoplasm; (4) release from contact sites; and (5) recycling of membrane receptors from the rear to the front of the cell. Each step is dependent upon one or more cyclical biochemical processes. The development of many in vitro and subcellular assays for the fundamental biochemical processes involved has increased our understanding of each cycle dramatically in the last several years to include a definition of many of the protein and enzymic components, the role of the position of extracellular-matrix receptors on the cell, and the contribution of physical force. The next generation of questions are directed at resolving the roles of the many individual proteins in each step of the cell migration process. In this chapter we will examine each of the migration steps and discuss the biochemical mechanisms that may underlie them.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M P Sheetz, D Felsenfeld, C G Galbraith, D Choquet. 1999. Cell migration as a five-step cycle.. https://pubmed.ncbi.nlm.nih.gov/10320942/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

L-selectin signaling of neutrophil adhesion and degranulation involves p38 mitogen-activated protein kinase.

The adhesion molecules known as selectins mediate the capture of neutrophils from the bloodstream. We have previously reported that ligation and cross-linking of L-selectin on the neutrophil surface enhances the adhesive function of beta(2)-integrins in a synergistic manner with chemotactic agonists. In this work, we examined degranulation and adhesion of neutrophils in response to cross-linking of L-selectin and addition of interleukin-8. Cross-linking of L-selectin induced priming of degranulation that was similar to that observed with the alkaloid cytochalasin B. Activation mediated by L-selectin of neutrophil shape change and adhesion through CD11b/CD18 were strongly blocked by Merck C, an imidazole-based inhibitor of p38 mitogen-activated protein kinase (MAPK), but not by a structurally similar non-binding regioisomer. Priming by L-selectin of the release of secondary, tertiary, and secretory, but not primary, granules was blocked by inhibition of p38 MAPK. Peak phosphorylation of p38 MAPK was observed within 1 min of cross-linking L-selectin, whereas phosphorylation of ERK1/2 was highest at 10 min. Phosphorylation of p38 MAPK, but not ERK1/2, was inhibited by Merck C. These data suggest that signal transduction as a result of clustering L-selectin utilizes p38 MAPK to effect neutrophil shape change, integrin activation, and the release of secondary, tertiary, and secretory granules.

Cell Adhesion

Factor XIIIa supports microvascular endothelial cell adhesion and inhibits capillary tube formation in fibrin.

Coagulation factor XIIIa is a transglutaminase that catalyzes covalent cross-link formation in fibrin clots. In this report, we demonstrate that factor XIIIa also mediates adhesion of endothelial cells and inhibits capillary tube formation in fibrin. The adhesive activity of factor XIIIa was not dependent on the transglutaminase activity, and did not involve the factor XIIIb-subunits. The adhesion was inhibited by 99% using a combination of monoclonal antibodies directed against integrin alpha(v)beta(3) and beta(1)-containing integrins, and was dependent on Mg(2+) or Mn(2+). Soluble factor XIIIa also bound to endothelial cells in solution, as detected by flow cytometry. In addition, factor XIIIa inhibited endothelial cell capillary tube formation in fibrin in a dose-dependent manner. Furthermore, the extent of inhibition differed in 2 types of fibrin. The addition of 10 to 100 microg/mL factor XIIIa produced a dose-dependent reduction in capillary tube formation of 60% to 100% in gammaA/gammaA fibrin, but only a 10% to 37% decrease in gammaA/gamma' fibrin. These results show that factor XIIIa supports endothelial cell adhesion in an integrin-dependent manner and inhibits capillary tube formation. (Blood. 2000;95:2586-2592)

Cell Adhesion

A versatile assay to study cellular uptake of gene transfer complexes by flow cytometry.

In this study, we present a simple and reliable method to analyse the first steps of DNA-based gene delivery into eucaryotic cells, i. e. binding and internalisation of transfection complexes. Taking advantage of flow cytometry, it is possible to discriminate quantitatively between total and internal DNA on a single-cell level. Here, we use two fluorescent dyes with high specificity and affinity to double-stranded DNA that cannot penetrate the extracellular membrane of living cells. Total DNA is stained prior to complexation with the first dye and complexes are added to cells. After the incubation, only extracellular DNA remains accessible to the second dye. Cell associated fluorescence is measured simultaneously using a flow cytometer and data are analysed using a computer program capable of calculating the ratio of fluorescence intensities on a single-cell level. These ratios are indicative of the binding and internalisation kinetics of gene transfer complexes.

Cell Adhesion